Numerous software applications (e.g., peer-to-peer applications) seek to initiate or take action when two wireless mobile devices (e.g., smartphones) are proximal to each other (i.e., within a preset distance). For instance, an online social game (e.g., FARMVILLE) can enable a player to use new powers when at least 3 ‘friends’ or ‘followers’ (e.g., FACEBOOK friends or followers on TWITTER) are simultaneously within a twenty foot radius of the player. Marketing applications may present advertisements or promotions to passersby of brick-and-mortar store. A dating application (e.g., SKOUT and ARE YOU INTERESTED) may enable users to view profiles of and communicate with other users who are nearby (e.g., in the same baseball stadium). Traditionally, proximity between communication devices has been determined by comparing locations of various devices where the locations are provided by the communication devices (e.g., via GPS).
However, privacy concerns and reception issues may make it undesirable or difficult to share or even know location information. Often, users do not wish to share location information, and even if they do, there are many instances where location information may not be known (e.g., limited GPS reception inside buildings), or may be too slow to acquire (e.g., a GPS signal can sometimes take a number of seconds, or even minutes to acquire).